iPad mini 2 activation server cannot be reached

Hi, I reset my iPad mini 2 (ios 9.3) after resetting and set up manually, it showed that my iPad could not be activated because the activation server cannot be reached. Try to connect it to iTunes. So I tried to connect it to iTunes, it showed that the iPad could not activated because the activation information could not be obtained from the device. And it said that the SIM card should be inserted correctly. But the iPad mini 2 has no sim insertion. I'm so confused. I even searched and watched about this problem but most of it have their sim card. I even updated and restored my iPad in iTunes but still, it still like that. I can't even contact the apple support saying that it is always limited. I always check it everyday. Please help me if you guys know something about this, here are the pictures.